Emulsion flow optimization method for suppresing vibration of cold continuous rolling mill

ABSTRACT

An emulsion flow optimization method suitable for a cold continuous rolling mill that aims to achieve vibration suppression. Said method aims to suppress vibrations, and by means of an oil film thickness model and a friction coefficient model, an optimum set value of the emulsion flow rate for each rolling stand that aims to achieve vibration suppression is optimized on the basis of an over-lubrication film thickness critical value and an under-lubrication film thickness critical value that are proposed. The described method greatly reduces the incidence of rolling mill vibration defects, improves production efficiency and product quality, treats rolling mill vibration defects, and improves the surface quality and rolling process stability of a finished strip of a cold continuous rolling mill.

TECHNICAL FIELD

The invention relates to the technical field of cold continuous rolling,in particular to an emulsion flow optimization method for suppressingvibration of a cold continuous rolling mill.

BACKGROUND

Rolling mill vibration defect is always one of the difficult problemsthat perplex the high-speed and stable production of an on-site coldcontinuous rolling mill and ensure the surface quality of finishedstrip. In the past, on-site treatment of rolling mill vibration defectsgenerally depends on the control over the speed of the rolling mill, bywhich the vibration defects can be weakened, but the improvement ofproduction efficiency is restricted and the economic benefits ofenterprises are seriously affected. However, for the cold continuousrolling mill, its device and process features determine the potential ofvibration suppression. Therefore, setting reasonable process parametersis the core means for vibration suppression. Through theoreticalresearch and on-the-spot tracking, it is found that the rolling millvibration is directly related to the lubrication state between the rollgaps. If the roll gaps are in an over-lubrication state, it is indicatedthat the friction coefficient is too small, thus it is likely to causeslip in the rolling process to cause the self-excited vibration of therolling mill; if the roll gap is in an under-lubrication state, it isindicated that the average oil film thickness between the roll gaps isless than the required minimum value, thus it is likely to cause sharpincrease of the friction coefficient due to rupture of oil films in theroll gaps during the rolling process, which leads to the change ofrolling pressure and periodic fluctuation of system stiffness, and thusalso causes self-excited vibration of the rolling mill. It can be seenthat the key to suppress the vibration of the rolling mill is to controlthe lubrication state between the roll gaps. On the premise that therolling schedule, the rolling process and process parameters such as theemulsion concentration and the initial temperature are determined, thesetting of emulsion flow rate directly determines the roll gaplubrication state of each rolling stand of the cold continuous rollingmill, and is the main process control means of the cold continuousrolling mill.

The patent No. 201410522168.9 discloses a cold continuous rolling millvibration suppression method, which comprises the following steps: 1)arranging a cold rolling mill vibration monitoring device on the fifthor fourth rolling stand of the cold continuous rolling mill, anddetermining whether the rolling mill is about to vibrate by the energyof a vibration signal; 2) arranging a liquid injection device which canindependently adjust the flow rate in front of an inlet emulsioninjection beam of the fifth or fourth rolling stand of the cold rollingmill; and 3) calculating the forward slip value to determine whether toturn on/off the liquid injection device. The patent No. 201410522168.9discloses a comprehensive emulsion flow optimization method forultra-thin strip rolling of a cold continuous rolling mill. The existingdevice parameters and process parameter data of a cold continuousrolling mill control system are used to define the process parameters ofcomprehensive emulsion flow optimization considering the slip, vibrationand hot slide injury as well as shape and pressure control, anddetermine the optimal flow rate distribution value of each rolling standunder the current tension schedule and rolling reduction schedule. Thecomprehensive optimization setting of emulsion flow rate for ultra-thinstrip rolling is realized by computer program control. The above patentsmainly focus on monitoring equipment, forward slip calculation model,emulsion flow rate control and other aspects to realize rolling millvibration control; vibration is only a constraint condition of emulsionflow rate control, and is not the main treatment object.

SUMMARY (I) Technical Problems Solved

The purpose of the invention is to provide an emulsion flow optimizationmethod for suppressing vibration of a cold continuous rolling mill. Themethod aims to suppress vibrations, and by means of an oil filmthickness model and a friction coefficient model, comprehensiveoptimization setting for the emulsion flow rate for each rolling standis realized on the basis of an over-lubrication film thickness criticalvalue and an under-lubrication film thickness critical value that areproposed so as to achieve the goals of treating rolling mill vibrationdefects, and improving the surface quality of a finished strip.

(II) Technical Solution

An emulsion flow optimization method for suppressing vibration of a coldcontinuous rolling mill includes the following steps:

S1, collecting device feature parameters of the cold continuous rollingmill, wherein the device feature parameters include: the radius R_(i) ofa working roll of each rolling stand, the surface linear velocity ν_(ri)of a roll of each rolling stand, the original roughness Ra_(ir0) of aworking roll of each rolling stand, the roughness attenuationcoefficient B_(L) of a working roll, the distance l between rollingstands, and the rolling kilometer L_(i) after roll change of a workingroll of each rolling stand, wherein i is 1, 2, . . . , n, and representsfor the ordinal number of rolling stands of the cold continuous rollingmill, and n is the total number of rolling stands;

S2, collecting key rolling process parameters of a strip, wherein thekey rolling process parameters include: the inlet thickness h_(0i) ofeach rolling stand, the outlet thickness h_(1i) of each rolling stand,strip width B, the inlet speed ν_(0i) of each rolling stand, the outletspeed ν_(1i) of each rolling stand, the inlet temperature T₁ ^(r), stripdeformation resistance K_(i) of each rolling stand, rolling pressureP_(i) of each rolling stand, back tension T_(0i) of each rolling stand,front tension T_(1i) of each rolling stand, emulsion concentrationinfluence coefficient k_(c), pressure-viscosity coefficient θ of alubricant, strip density ρ, specific heat capacity S of a strip,emulsion concentration C, emulsion temperature T_(c) and thermal-workequivalent J;

S3, defining process parameters involved in the process of emulsion flowoptimization, wherein the process parameters include that anover-lubrication film thickness critical value of each rolling stand isξ_(i) ⁺ and the friction coefficient at this time is u_(i) ⁺, anunder-lubrication film thickness critical value is and the frictioncoefficient at this time is u_(i) ⁻, the rolling reduction amount isΔh_(i),h_(0i)−h_(1i), the rolling reduction rate is

${ɛ_{i} = \frac{\Delta\; h_{i}}{h_{0i}}},$

and the inlet temperature of each rolling stand is T_(i) ^(r), thedistance l between the rolling stands is evenly divided into m sections,and the temperature in the sections is represented by T_(i,j) (wherein,1≤j≤m), and T_(i) ^(r)=T_(i−1,m) the over-lubrication judgmentcoefficient is A⁺, and the under-lubrication judgment coefficient is A⁻;

S4, setting the initial set value of an emulsion flow rate comprehensiveoptimization objective function of the cold continuous rolling mill thataims to achieve vibration suppression as F₀=1.0×10¹⁰;

wherein the executing order of steps S1 to S4 is not limited.

S5, calculating the bite angle α_(i) of each rolling stand according tothe rolling theory, wherein the calculation formula is as follows:

${\alpha_{i} = \sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}},$

R_(i)′ is the flattening radius of the working roll of the i^(th)rolling stand, and is the calculation process value of rolling pressure;

S6, calculating the vibration determination index reference value ξ_(0i)of each rolling stand;

S7, setting the emulsion flow rate w_(i) of each rolling stand;

S8, calculating the strip outlet temperature T_(i) of each rollingstand;

S9, calculating an emulsion flow rate comprehensive optimizationobjective function F(X):

$\quad\left\{ \begin{matrix}{{F(X)} = {{\frac{\lambda}{n}{\sum\limits_{i = 1}^{n}\sqrt{\left( {\xi_{i} - \xi_{0i}} \right)^{2}}}} + {\left( {1 - \lambda} \right)\mspace{14mu}\max\mspace{11mu}{{\xi_{i} - \xi_{0i}}}}}} \\{\xi_{i}^{-} < \xi_{i} < \xi_{i}^{+}}\end{matrix} \right.$

S10, determination whether the in-equation F(X)<F₀ is established, ifyes, enabling w_(i) ^(y)=w_(i),F₀=F(X), and then turning to step S11,since F₀=1.0×10¹⁰ under the initial circumstance, the value is verylarge, in the first calculation process, F(X) must be smaller than F₀,and in the subsequent x calculation processes, the corresponding F(X) isobtained with the change of w_(i), and the x^(th) F₀ is thex−1^(th)F(X), if the x^(th) F(X) is smaller than the x−1^(th)F(X), it isdetermined that F(X)<F₀ is established and turn to step S11; otherwise,turning directly to step S11;

S11, determining whether the emulsion flow rate w_(i) exceeds a feasibleregion range, if yes, turning to step S12; otherwise, turning to stepS7, wherein the feasible region of w_(i) ranges from 0 to the maximumemulsion flow rate value allowed by the rolling mill.

S12, outputting an optimal emulsion flow rate set value w_(i)′, whereinw_(i) ^(y) is the value of w_(i) when the calculated value of F(X) inthe feasible region is minimum.

According to an embodiment of the present invention, the step S6includes the following steps:

S6.1, calculating the neutral angle γ_(i) of each rolling stand:

${\gamma_{i} = {\frac{1}{2}{\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}\left\lbrack {1 + {\frac{1}{2u}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}} \right\rbrack}}};$

S6.2, calculating to obtain

$u_{i}^{+}\frac{1}{2\left( {{2A^{+}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)$

from steps S5 and S6.1 assuming that when

${\frac{\gamma_{i}}{\alpha_{i}} = A^{+}},$

the roll gap is just in an over-lubrication state;

S6.3, calculating an over-lubrication film thickness critical valueξ_(i) ⁺ of each rolling stand according to the relationship formulabetween the friction coefficient and the oil film thickness, namelyu_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) (in the formula, a_(i) is theliquid friction influence coefficient, b_(i) is the dry frictioninfluence coefficient, and B_(i) is the friction coefficient attenuationindex), wherein

${\xi_{i}^{+} = {\frac{1}{B_{i}}\;\ln\;\frac{u_{i}^{+} - a_{i}}{b_{i}}}};$

S6.4, calculating to obtain

$u_{i}^{-} = {\frac{1}{2\left( {{2A^{-}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}$

from steps S5 and S6.1 assuming that when

${\frac{\gamma_{i}}{\alpha_{i}} = A^{-}},$

the roll gap is Just in an under-lubrication state;

S6.5, calculating an under-lubrication film thickness critical valueξ_(i) ⁻ of each rolling stand according to the relationship formulabetween the friction coefficient and the oil film thickness, namelyu_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) , wherein

${\xi_{i}^{-} = {\frac{1}{B_{i}}\;\ln\;\frac{u_{i}^{-} - a_{i}}{b_{i}}}};$

and

S6.6, calculating the vibration determination index reference valueξ_(0i) of each rolling stand, wherein

$\xi_{0i} = {\frac{\xi_{i}^{+} + \xi_{i}^{-}}{2}.}$

According to an embodiment of the present invention, the step S8includes the following steps:

S8.1, calculating the outlet temperature T₁ of the first rolling stand,wherein

${T_{1} = {T_{1}^{r} + {\frac{1 - \left( {ɛ_{1}/4} \right)}{1 - \left( {ɛ_{1}/2} \right)} \cdot \frac{K_{1}\;{\ln\left( \frac{1}{1 - ɛ_{1}} \right)}}{\rho\;{SJ}}}}};$

S8.2, enabling i=1;

S8.3, calculating the temperature T_(i,1) of the first section of stripbehind the outlet of the i^(th) rolling stand, i.e. T_(i,1)=T_(i);

S8.4, enabling j=2;

S8.5, showing the relationship between the temperature of the j^(th)section and the temperature of the j−1^(th) section by the followingequation:

${T_{i,j} = {{{- \frac{2k_{0}w^{0.264}\exp\;\left( {{9.45} - {{0.1}918C}} \right) \times {1.1}63l}{v_{1i}h_{1i}\rho\;{Sm}}}{T_{i,{j - 1}}^{- 0.213}\left( {T_{i,{j - 1}} - T_{c}} \right)}} + T_{i,{j - 1}}}},$

wherein k₀ is the influence coefficient of the nozzle shape and sprayingangle, and 0.8<k₀<1.2;

S8.6, determining whether the in-equation j<m is established, if yes,enabling j=j+1, and then turning to step S8.5; otherwise, turning tostep S8.7;

S8.7, obtaining the temperature T_(i,m) of the m^(th) section byiterative calculation;

S8.8, calculating the inlet temperature T_(i+1) ^(r) of the i+1^(th)rolling stand: T_(i+1) ^(r)=T_(i,m);

S8.9, calculating the outlet temperature T_(i+1) of the i+1^(th) rollingstand, wherein

${T_{i + 1} = {T_{i + 1}^{r} + {\frac{1 - \left( {ɛ_{i + 1}/4} \right)}{1 - \left( {ɛ_{i + 1}/2} \right)} \cdot \frac{K_{i + 1}{\ln\left( \frac{1}{1 - ɛ_{i + 1}} \right)}}{\rho\;{SJ}}}}};$

S8.10, determining whether the in-equation i<n is established, if yes,enabling i=i+1, and then turning to step S8.3; otherwise, turning tostep S8.11; and

S8.11, obtaining the outlet temperature T_(i) of each rolling stand.

According to an embodiment of the present invention, the step S9includes the following steps:

S9.1, calculating the dynamic viscosity η_(0i) of an emulsion betweenroll gaps of each rolling stand, wherein η_(0i)b·exp(−a·T_(i)), in theformula, a,b are the dynamic viscosity parameters of lubricating oilunder atmospheric pressure;

S9.2, calculating the oil film thickness ξ_(i) between the roll gaps ofeach rolling stand, wherein the calculation formula is as follows:

$\xi_{i} = {{\frac{h_{0i} + h_{1i}}{2h_{0\; i}} \cdot k_{c} \cdot \frac{3\theta\;{\eta_{0\; i}\left( {v_{ri} + v_{0\; i}} \right)}}{\alpha_{i}\left\lbrack {1 - e^{- {\theta{({K - \frac{T_{0\; i}}{h_{0\; i} \cdot B}})}}}} \right\rbrack}} - {k_{rg} \cdot \left( {1 + K_{rs}} \right) \cdot {Ra}_{{ir}\; 0} \cdot e^{{- B_{L}} \cdot L_{i}}}}$

in the formula, k_(rg) represents the coefficient of the strength ofentrainment of lubricant by the longitudinal surface roughness of thework roll and the strip steel, and is in the range of 0.09-0.15, andK_(rs) represents the impression rate, that is, the ratio oftransferring the surface roughness of the working roll to the strip; and

S9.3, calculating an emulsion flow rate comprehensive optimizationobjective function

$\quad\left\{ \begin{matrix}{{F(X)} = {{\frac{\lambda}{n}{\sum\limits_{i = 1}^{n}\sqrt{\left( {\xi_{i} - \xi_{0i}} \right)^{2}}}} + {\left( {1 - \lambda} \right)\mspace{14mu}\max\mspace{11mu}{{\xi_{i} - \xi_{0i}}}}}} \\{\xi_{i}^{-} < \xi_{i} < \xi_{i}^{+}}\end{matrix} \right.$

in the formula, X={w_(i)} is the optimization variable and λ is thedistribution coefficient.

In the present application, as long as the next step is not conditionalon the result of the previous step, it is not necessary to follow thesteps, unless the next step depends on the previous step.

(III) Beneficial Effects

the technical solution of the invention is adopted, and the emulsionflow optimization method for suppressing vibration of the coldcontinuous rolling mill fully combines the device and process featuresof the cold continuous rolling mill, and aiming at the problems ofvibration defects, starting from the comprehensive optimization settingfor the emulsion flow rate of each rolling stand and changing theprevious idea of constant emulsion flow control for each rolling standof the cold continuous rolling mill, the method obtains the optimal setvalue of the emulsion flow rate for each rolling stand that aims toachieve vibration suppression by optimization; and the method greatlyreduces the incidence of rolling mill vibration defects, improvesproduction efficiency and product quality, brings greater economicbenefits for enterprises, treats rolling mill vibration defects, andimproves the surface quality and rolling process stability of a finishedstrip of a cold continuous rolling mill.

BRIEF DESCRIPTION OF THE DRAWINGS

In the present invention, the same reference numerals always representthe same features, wherein:

FIG. 1 is a flowchart of an emulsion flow optimization method of thepresent invention;

FIG. 2 is a flowchart of calculating the vibration determination indexreference value;

FIG. 3 is a flowchart of calculating the strip outlet temperature ofeach rolling stand; and

FIG. 4 is a flowchart of calculating an emulsion flow comprehensiveoptimization objective function.

DETAILED DESCRIPTION

The technical solution of the present invention will be furtherdescribed in combination with the drawings and the embodiments.

Rolling mill vibration defects are very easily caused between roll gapsof each rolling stand of a cold continuous rolling mill, whether in anover-lubrication state or in an under-lubrication state, and the settingof the emulsion flow rate directly affects the lubrication state betweenthe roll gaps of each rolling stand. In order to realize the treatmentof the rolling mill vibration defects, starting from the emulsion flowrate, this patent ensures that both the overall lubrication state of thecold continuous rolling mill and the lubrication state of individualrolling stands can be optimum through the comprehensive optimaldistribution of the emulsion flow rate of the cold continuous rollingmill, so as to achieve the goal of treating the rolling mill vibrationdefects, improving the surface quality and rolling process stability ofa finished strip of the cold continuous rolling mill.

Referring to FIG. 1, an emulsion flow optimization method forsuppressing vibration of a cold continuous rolling mill includes thefollowing steps:

S1, collecting device feature parameters of the cold continuous rollingmill, wherein the device feature parameters include: the radius R_(i) ofa working roll of each rolling stand, the surface linear velocity ν_(ri)of a roll of each rolling stand, the original roughness Ra_(ir0) of aworking roll of each rolling stand, the roughness attenuationcoefficient B_(L) of a working roll, the distance l between rollingstands, and the rolling kilometer L_(i) after roll change of a workingroll of each rolling stand, wherein i is 1, 2, . . . , n, and representsthe ordinal number of rolling stands of the cold continuous rollingmill, and n is the total number of rolling stands;

S2, collecting key rolling process parameters of a strip, wherein thekey rolling process parameters include: the inlet thickness h_(0i) ofeach rolling stand, the outlet thickness h_(1i) of each rolling stand,strip width B, the inlet speed ν_(0i) of each rolling stand, the outletspeed ν_(1i) of each rolling stand, the inlet temperature T₁ ^(r), stripdeformation resistance K_(i) of each rolling stand, rolling pressureP_(i) of each rolling stand, back tension T_(0i) of each rolling stand,front tension T_(1i) of each rolling stand, emulsion concentrationinfluence coefficient k_(c), pressure-viscosity coefficient θ of alubricant, strip density ρ, specific heat capacity S of a strip,emulsion concentration C, emulsion temperature T_(c) and thermal-workequivalent J;

S3, defining process parameters involved in the process of emulsion flowoptimization, wherein the process parameters include that anover-lubrication film thickness critical value of each rolling stand isξ_(i) ⁺ and the friction coefficient at this time is u_(i) ⁺, anunder-lubrication film thickness critical value is ξ_(i) ⁺ and thefriction coefficient at this time is u_(i) ⁻, the rolling reductionamount is Δh_(i)=h_(0i)−h_(1i), the rolling reduction rate is

${ɛ_{i} = \frac{\Delta\; h_{i}}{h_{0\; i}}},$

the inlet temperature of each rolling stand is T_(i) ^(r), the distancel between the rolling stands is evenly divided into m sections, and thetemperature in the sections is represented by T_(i,j)(wherein, 1≤j≤m),and T_(i) ^(r)=T_(i−1,m), the over-lubrication judgment coefficient isA⁺, and the under-lubrication judgment coefficient is A⁻;

S4, setting the initial set value of an emulsion flow rate comprehensiveoptimization objective function of the cold continuous rolling mill thataims to achieve vibration suppression as F₀=1.0×10¹⁰;

the executing order of steps S1 to S4 is not limited, and in some cases,steps S1 to S4 can be performed simultaneously.

S5, calculating the bite angle α_(i) of each rolling stand according tothe rolling theory, wherein the calculation formula is as follows:

${\alpha_{i} = \sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}},$

R_(i)′ is the flattening radius of the working roll of the i^(th)rolling stand, and is the calculation process value of rolling pressure;

S6, calculating the vibration determination index reference value ξ_(0i)of each rolling stand, wherein the calculation flowchart is shown inFIG. 2:

S6.1, calculating the neutral angle γ_(i) of each rolling stand:

${\gamma_{i} = {\frac{1}{2}{\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}\left\lbrack {1 + {\frac{1}{2u_{i}}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}} \right\rbrack}}};$

S6.2, calculating to obtain

$u_{i}^{+} = {\frac{1}{2\left( {{2A^{+}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}$

from steps S5 and S6.1 assuming that when

${\frac{\gamma_{i}}{\alpha_{i}} = A^{+}},$

the roll gap is Just in an over-lubrication state;

S6.3, calculating an over-lubrication film thickness critical valueξ_(i) ⁺ of each rolling stand according to the relationship formulabetween the friction coefficient and the oil film thickness, namelyu_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) (in the formula, a_(i) is theliquid friction influence coefficient, b_(i) is the dry frictioninfluence coefficient, and B_(i) is the friction coefficient attenuationindex), wherein

${\xi_{i}^{+} = {\frac{1}{B_{i}}\ln\;\frac{u_{i}^{+} - a_{i}}{b_{i}}}};$

S6.4, calculating to obtain

$u_{i}^{-} = {\frac{1}{2\left( {{2A^{-}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}$

from steps S5 and S6.1 assuming that when

${\frac{\gamma_{i}}{\alpha_{i}} = A^{-}},$

the roll gap is just in an under-lubrication state;

S6.5, calculating an under-lubrication film thickness critical value ofξ_(i) ⁻ each rolling stand according to the relationship formula betweenthe friction coefficient and the oil film thickness, namelyu_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) , wherein

${\xi_{i}^{-} = {\frac{1}{B_{i}}\ln\;\frac{u_{i}^{-} - a_{i}}{b_{i}}}};$

and

S6.6, calculating the vibration determination index reference valueξ_(0i) of each rolling stand, wherein

${\xi_{0i}\frac{\xi_{i}^{+} + \xi_{i}^{-}}{2}};$

S7, setting the emulsion flow rate w_(i) of each rolling stand;

S8, calculating the strip outlet temperature T_(i) of each rollingstand, wherein the calculation flowchart is shown in FIG. 3,

S8.1, calculating the outlet temperature T₁ of the first rolling stand,wherein

${T_{1} = {T_{1}^{r} + {\frac{1 - \left( {ɛ_{1}\text{/}4} \right)}{1 - \left( {ɛ_{1}\text{/}2} \right)} \cdot \frac{K_{1}\ln\;\left( \frac{1}{1 - ɛ_{1}} \right)}{\rho\; S\; J}}}};$

S8.2, enabling i=1;

S8.3, calculating the temperature T_(i,1) of the first section of stripbehind the outlet of the i^(th) rolling stand, i.e. T_(i,1)=T_(i);

S8.4, enabling j=2;

S8.5, showing the relationship between the temperature of the j^(th)section and the temperature of the j−1^(th) section by the followingequation:

${T_{i,j} = {{{- \frac{2k_{0}w_{i}^{0.264}{\exp\left( {9.45 - {{0.1}918C}} \right)} \times {1.1}63l}{v_{1i}h_{1i}\rho Sm}}{T_{i,{j - 1}}^{- 0.213}\left( {T_{i,{j - 1}} - T_{c}} \right)}} + T_{i,{j - 1}}}},$

wherein k₀ is the influence coefficient of the nozzle shape and sprayingangle, and 0.8<k₀<1.2;

S8.6, determining whether the in-equation j<m is established, if yes,enabling j=j+1, and then turning to step S8.5; otherwise, turning tostep S8.7;

S8.7, obtaining the temperature T_(i,m) of the m^(th) section byiterative calculation;

S8.8, calculating the inlet temperature T_(i+1) ^(r) of the i+1^(th)rolling stand: T_(i+1) ^(r)=T_(i,m);

S8.9, calculating the outlet temperature T_(i+1) of the i+1^(th) rollingstand, wherein

${T_{i + 1} = {T_{i + 1}^{r} + {\frac{1 - \left( {ɛ_{i + 1}\text{/}4} \right)}{1 - \left( {ɛ_{i + 1}\text{/}2} \right)} \cdot \frac{K_{i + 1}\ln\;\left( \frac{1}{1 - ɛ_{i + 1}} \right)}{\rho\;{SJ}}}}};$

S8.10, determining whether the in-equation i<n is established, if yes,enabling i=i+1, and then turning to step S8.3; otherwise, turning tostep S8.11; and

S8.11, obtaining the outlet temperature T_(i) of each rolling stand;

S9, calculating an emulsion flow rate comprehensive optimizationobjective function F(X), wherein the calculation flowchart is shown inFIG. 4,

S9.1, calculating the dynamic viscosity η_(0i), of an emulsion betweenroll gaps of each rolling stand, wherein η_(0i)b·exp(−a·T_(i)), in theformula, a,b are the dynamic viscosity parameters of lubricating oilunder atmospheric pressure;

S9.2, calculating the oil film thickness ξ_(i) between the roll gaps ofeach rolling stand, wherein the calculation formula is as follows:

$\xi_{i} = {{\frac{h_{0i} + h_{1i}}{2h_{0i}} \cdot k_{c} \cdot \frac{3\theta{\eta_{0i}\left( {v_{ri} + v_{0i}} \right)}}{\alpha_{i}\left\lbrack {1 - e^{- {\theta{({K - \frac{T_{0i}}{h_{0i} \cdot B}})}}}}\; \right\rbrack}} - {k_{rg} \cdot \left( {1 + K_{rs}} \right) \cdot {Ra}_{{ir}\; 0} \cdot e^{{- B_{L}} \cdot L_{i}}}}$

in the formula, k_(rg) represents the coefficient of the strength ofentrainment of lubricant by the longitudinal surface roughness of thework roll and the strip steel, and is in the range of 0.09-0.15, andK_(rs) represents the impression rate, that is, the ratio oftransferring the surface roughness of the working roll to the strip; and

S9.3, calculating an emulsion flow rate comprehensive optimizationobjective function:

$\quad\left\{ \begin{matrix}{{F(X)} = {{\frac{\lambda}{n}{\sum\limits_{i = 1}^{n}\sqrt{\left( {\xi_{i} - \xi_{0i}} \right)^{2}}}} + {\left( {1 - \lambda} \right)\max{{\xi_{i} - \xi_{0i}}}}}} \\{\xi_{i}^{-} < \xi_{i} < \xi_{i}^{+}}\end{matrix} \right.$

in the formula, X={w_(i)} is the optimization variable and λ is thedistribution coefficient;

S10, determining whether the in-equation F(X)<F₀ is established, if yes,enabling w_(i) ^(y)=w_(i),F₀=F(X), and then turning to step S11;otherwise, turning directly to step S11;

S11, determining whether the emulsion flow rate w_(i) exceeds the afeasible region range, if yes, turning to step S12; otherwise, turningto step S7, wherein the feasible region of w_(i) ranges from 0 to themaximum emulsion flow rate value allowed by the rolling mill.

S12, outputting an optimal emulsion flow rate set value w_(i) ^(y),wherein w_(i) ^(y) is the value of w_(i) when the calculated value ofF(X) in the feasible region is minimum.

Embodiment 1

In order to further explain the application process of the relatedtechnology of the present application, the application process of anemulsion flow optimization method for a cold continuous rolling millthat aims to achieve vibration suppression is described by taking a 1730cold continuous rolling mill in a cold rolling plant as an example.

An emulsion flow optimization method for suppressing vibration of a coldcontinuous rolling mill includes the following steps:

S1, collecting device feature parameters of the cold continuous rollingmill, wherein the 1730 cold continuous rolling mill in a cold rollingplant has 5 rolling stands in total, and the device feature parametersmainly include: the radius R_(i)={210,212,230,230,228} mm of a workingroll of each rolling stand, the surface linear velocityν_(ri)={180,320,500,800,1150} m/min of a roll of each rolling stand, theoriginal roughness Ra_(ir0)={1.0,1.0,0.8,0.8,1.0} um of a working rollof each rolling stand, the roughness attenuation coefficient B_(L)=0.01of a working roll, the distance l=2700 mm between rolling stands, andthe rolling kilometer L_(i)={100,110,230,180,90} km after roll change ofa working roll of each rolling stand, wherein i is 1, 2, . . . , n, andrepresents the ordinal number of rolling stands of the cold continuousrolling mill, and n=5 is the total number of rolling stands, the samebelow;

S2, collecting key rolling process parameters of a strip, wherein thekey rolling process parameters mainly include: the inlet thicknessh_(0i)={2.0,1.14,0.63,0.43,0.28} mm of each rolling stand, the outletthickness h_(1i)={1.14,0.63,0.43,0.28,0.18} mm of each rolling stand,strip width B=966 mm, the inlet speed ν_(0i)={110,190,342,552,848} m/minof each rolling stand, the outlet speed ν_(1i)={190,342,552,848,1214}m/min of each rolling stand, the inlet temperature T₁ ^(r)=110° C.,strip deformation resistance K_(i)={360,400,480,590,650} MPa of eachrolling stand, rolling pressure P_(i)={12800,11300,10500,9600,8800} kNof each rolling stand, back tension T_(0i){70,145,208,202,229} MPa ofeach rolling stand, front tension T_(1i)={145,208,202,229,56} MPa ofeach rolling stand, emulsion concentration influence coefficientk_(c)=0.9, pressure-viscosity coefficient θ=0.034 of a lubricant, stripdensity ρ=7800 kg/m³, specific heat capacity S=0.47 kJ/(kg·° C.) of astrip, emulsion concentration C=4.2%, emulsion temperature T_(c)=58° C.and thermal-work equivalent J=1;

S3, defining process parameters involved in the process of emulsion flowoptimization, wherein the process parameters mainly include that anover-lubrication film thickness critical value of ξ_(i) ⁺ each rollingstand is and the friction coefficient at this time is u_(i) ⁺, anunder-lubrication film thickness critical value is ξ_(i) ⁻ and thefriction coefficient at this time is u_(i) ⁻, the rolling reductionamount is Δh_(i)=h_(0i)−h_(1i), the rolling reduction rate is

${ɛ_{i}\frac{\Delta\; h_{i}}{h_{0i}}},$

the inlet temperature of each rolling stand is T_(i) ^(r), and thedistance l=2700 mm between the rolling stands is evenly divided intom=30 sections, and the temperature in the sections is represented byT_(i,j) (wherein, 1≤j≤m), and T_(i) ^(r)=T_(i−1,m), the over-lubricationjudgment coefficient is A⁺, and the under-lubrication judgmentcoefficient is A⁻;

S4, setting the initial set value of an emulsion flow rate comprehensiveoptimization objective function of a cold continuous rolling mill thataims to achieve vibration suppression as F₀=1.0×10¹⁰;

S5, calculating the bite angle α_(i) of each rolling stand according tothe rolling theory, wherein the calculation formula is

${\alpha_{i} = \sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}},$

from which it can be obtained thatα_(i)=10.0556,0.0427,0.0258,0.0223,0.01841;

S6, calculating the vibration determination index reference value ξ_(0i)of each rolling stand;

S6.1, calculating the neutral angle γ_(i) of each rolling stand, whereinthe calculation formula is

${\gamma_{i} = {\frac{1}{2}{\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}\left\lbrack {1 + {\frac{1}{2u_{i}}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}} \right\rbrack}}};$

S6.2, calculating to obtain u_(i) ⁺={0.0248,0.0186,0.0132,0.0136,0.0191}according to the formula

$u_{i}^{+} = {\frac{1}{2\left( {{2A^{+}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}$

from steps S5 and S6.1 assuming that when

${\frac{\gamma_{i}}{\alpha_{i}} = {A^{+} = 1}},$

the roll gap is just in an over-lubrication state;

S6.3, calculating an over-lubrication film thickness critical value ofξ_(i) ⁺ each rolling stand according to the relationship formula betweenthe friction coefficient and the oil film thickness, i.e.u_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) (in the formula, a_(i) is theliquid friction influence coefficient, a_(i)=0.0126, b_(i) is the dryfriction influence coefficient, b_(i)=0.1416, and B_(i) is the frictioncoefficient attenuation index, B_(i)=−2.4297), wherein the calculationformula is

${\xi_{i}^{+} = {\frac{1}{B_{i}}\ln\frac{u_{i}^{+} - a_{i}}{b_{i}}}},$

from which it can be obtained that: ξ_(i)⁻={1.009,1.301,2.249,2.039,1.268} um;

S6.4, calculating to obtain u_(i) ⁻={0.1240,0.0930,0.0660,0.0680,0.0955}according to the formula

$u_{i}^{-} = {\frac{1}{2\left( {{2A^{-}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}$

from steps S5 and S6.1 assuming that when

${\frac{\gamma_{i}}{\alpha_{i}} = {A^{-} = {0.6}}},$

the roll gap is just in an under-lubrication state;

S6.5, calculating an under-lubrication film thickness critical value ofξ_(i) ⁻ each rolling stand according to the relationship formula betweenthe friction coefficient and the oil film thickness, i.e.u_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) , wherein the calculationformula is

${\xi_{i}^{-} = {\frac{1}{B_{i}}\ln\frac{u_{i}^{-} - a_{i}}{b_{i}}}},$

from which it can be obtained that: ξ_(i)⁻={0.098,0.233,0.401,0.386,0.220} um;

S6.6, calculating the vibration determination index reference valueξ_(0i), wherein

${\xi_{0i} = \frac{\xi_{i}^{+} + \xi_{i}^{-}}{2}},$

from which it can be obtained that:ξ_(0i)={0.554,0.767,1.325,1.213,0.744};

S7. Setting the emulsion flow rate of each rolling stand to bew_(i)={900,900,900,900,900} L/min;

S8, calculating the strip outlet temperature T_(i) of each rollingstand,

S8.1, calculating the outlet temperature T₁ of the first rolling stand,

$T_{1} = {{T_{1}^{r} + {\frac{1 - \left( {ɛ_{1}/4} \right)}{1 - \left( {ɛ_{1}/2} \right)} \cdot \frac{K_{1}{\ln\left( \frac{1}{1 - ɛ_{1}} \right)}}{\rho\;{SJ}}}} = {{{110} + {\frac{1 - \left( {0.4{3/4}} \right)}{1 - \left( {0.43/2} \right)} \cdot \frac{360{\ln\left( \frac{1}{1 - {{0.4}3}} \right)}}{7.8 \cdot 0.47 \cdot 1}}} = {172.76{^\circ}\mspace{14mu}{C.}}}}$

S8.2, enabling i=1;

S8.3, calculating the temperature T_(1,1), of the first section of stripbehind the outlet of the first rolling stand, i.e. T_(i,1)=T_(i)=172.76°C.;

S8.4, enabling j=2;

S8.5, showing the relationship formula between the temperature of thej^(th) section and the temperature of the j−1^(th) section by thefollowing equation:

${T_{i,j} = {{{- \frac{2k_{0}w_{i}^{0.264}{\exp\left( {{{9.4}5} - {0.1918\mspace{14mu}{C.}}} \right)} \times 1.163l}{v_{1i}h_{1i}\rho Sm}}{T_{i,{j - 1}}^{- 0.213}\left( {T_{i,{j - 1}} - T_{c}} \right)}} + T_{i,{j - 1}}}},$

wherein k₀=1.0;

S8.6, determining whether the in-equation j<m is established: if yes,enabling j=j+1. and then turning to step S8.5; otherwise, turning tostep S8.7;

S8.7, obtaining the temperature T_(1,30)=103.32° C. of the m=30^(th)section by iterative calculation finally;

S8.8, calculating the inlet temperature T₂ ^(r) of the second rollingstand: T₂ ^(r)=T_(1,m)=103.32° C.;

S8.9, calculating the outlet temperature T₂ of the second rolling stand:

${T_{2} = {{T_{2}^{r} + {\frac{1 - \left( {ɛ_{2}/4} \right)}{1 - \left( {ɛ_{2}/2} \right)} \cdot \frac{K_{2}{\ln\left( \frac{1}{1 - ɛ_{2}} \right)}}{\rho\;{SJ}}}} = {{{10{3.3}2} + {\frac{1 - \left( {0.4{5/4}} \right)}{1 - \left( {0.45/2} \right)} \cdot \frac{400{\ln\left( \frac{1}{1 - {{0.4}5}} \right)}}{7800 \cdot 0.47 \cdot 1}}} = {178.02{^\circ}\mspace{14mu}{C.}}}}};$

S8.10, determining whether the in-equation i<n is established: if yes,enabling i=i+1, and then turning to step S8.3; otherwise, turning tostep S8.11;

S8.11, obtaining the outlet temperatureT_(i)={172.76,178.02,186.59,194.35,206.33}° C. of each rolling stand;

S9, calculating an emulsion flow rate comprehensive optimizationobjective function F(X);

S9.1, calculating the dynamic viscosity η_(0i) of an emulsion betweenroll gaps of each rolling stand, wherein η_(0i)=b·exp(−a·T_(i)), in theformula, a,b are the dynamic viscosity parameters of lubricating oilunder atmospheric pressure, and it can be obtained from a=0.05, b=2.5that η_(0i)={5.39,5.46,5.59,5.69,5.84};

S9.2, calculating the oil film thickness ξ_(i) between the roll gaps ofeach rolling stand according to the following formula:

$\xi_{i} = {{\frac{h_{0i} + h_{1i}}{2h_{0i}} \cdot k_{c} \cdot \frac{3\theta{\eta_{0i}\left( {v_{ri} + v_{0i}} \right)}}{\alpha_{i}\left\lbrack {1 - e^{- {\theta{({K - \frac{T_{0i}}{h_{0i} \cdot B}})}}}} \right\rbrack}} - {k_{rg} \cdot \left( {1 + K_{rs}} \right) \cdot {Ra}_{{ir}\; 0} \cdot e^{{- B_{Li}}L_{i}}}}$

wherein in the formula, k_(rg) represents the coefficient of thestrength of entrainment of lubricant by the longitudinal surfaceroughness of the work roll and the strip steel, k_(rg)=1.183, and K_(rs)represents the impression rate, that is, the ratio of transferring thesurface roughness of the working roll to the strip, K_(rs)=0.576, fromwhich it can be obtained that: ξ_(i)={0.784,0.963,2.101,2.043,1.326} um;

S9.3, calculating an emulsion flow rate comprehensive optimizationobjective function:

$\left\{ {\begin{matrix}{{F(X)} = {{\frac{\lambda}{n}{\sum\limits_{i = 1}^{n}\sqrt{\left( {\xi_{i} - \xi_{0i}} \right)^{2}}}} + {\left( {1 - \lambda} \right)\max{{\xi_{i} - \xi_{0i}}}}}} \\{\xi_{i}^{-} < \xi_{i} < \xi_{i}^{+}}\end{matrix}\quad} \right.$

in the formula, X={w_(i)} is the optimization variable, λ=0.5 is thedistribution coefficient, and thus F(X)=0.94;

S10, enabling w_(i) ^(y)=w_(i)={900,900,900,900,900}L/min ifF(X)=0.94<F₀=1×10¹⁰ is established, F₀=F(X)=0.94, turning to step S11,wherein in the subsequent x calculation processes, the correspondingF(X) is obtained with the change of w_(i), and the x^(th) F₀ is thex−1^(th) F(X). If the x^(th) F(X) is smaller than the x−1^(th) F(X), itis judged that F(X)<F₀ is established and turn to step S11;

S11, determining whether the emulsion flow rate w_(i) exceeds thefeasible region range. If yes, turning to step S12; otherwise, turningto step S7; and

S12, outputting an optimal emulsion flow rate set value w_(i)^(y)={1022,1050,1255,1698,1102}L/min.

Embodiment 2

In order to further explain the application process of the relatedtechnology of the present application, the application process of anemulsion flow optimization method for a cold continuous rolling millthat aims to achieve vibration suppression is described by taking a 1420cold continuous rolling mill in a cold rolling plant as an example.

An emulsion flow optimization method for suppressing vibration of a coldcontinuous rolling mill includes the following steps:

S1, collecting device feature parameters of the cold continuous rollingmill, wherein the 1420 cold continuous rolling mill in a cold rollingplant has 5 rolling stands in total, and the device feature parametersmainly include: the radius R_(i){211,213,233,233,229} mm of a workingroll of each rolling stand, the surface linear velocityν_(ri)={182,322,504,805,1153} m/min of a roll of each rolling stand, theoriginal roughness Ra_(ir0)={1.0,1.0,0.9,0.9,1.0} um of a working rollof each rolling stand, the roughness attenuation coefficient B_(L)=0.015of a working roll, the distance l=2750 mm between rolling stands, andthe rolling kilometer L_(i)={120,130,230,190,200} km after roll changeof a working roll of each rolling stand, wherein i is 1, 2, . . . , n,and represents the ordinal number of rolling stands of the coldcontinuous rolling mill, and n=5 is the total number of rolling stands,the same below;

S2, collecting key rolling process parameters of a strip, wherein thekey rolling process parameters mainly include: the inlet thicknessh_(0i)={2.1,1.15,0.65,0.45,0.3} mm of each rolling stand, the outletthickness h_(1i)={1.15,0.65,0.45,0.3,0.15} mm of each rolling stand,strip width B=955 mm, the inlet speed ν_(0i)={115,193,346,555,852} m/minof each rolling stand, the outlet speed ν_(1i)={191,344,556,849,1217}m/min of each rolling stand, the inlet temperature T₁ ^(r)=115° C.,strip deformation resistance K_(i)={370,410,490,590,660} MPa of eachrolling stand, rolling pressure P_(i)={12820,11330,10510,9630,8820} kNof each rolling stand, back tension T_(0i)={73,148,210,205,232}MPa ofeach rolling stand, front tension T_(1i)={147,212,206,231,60} MPa ofeach rolling stand, emulsion concentration influence coefficientk_(c)=0.9, pressure-viscosity coefficient θ=0.036 of a lubricant, stripdensity ρ=7800 kg/m³, specific heat capacity S=0.49 kJ/(kg·° C.) of astrip, emulsion concentration C=4.5%, emulsion temperature T_(c)=59° C.and thermal-work equivalent J=1;

S3, defining process parameters involved in the process of emulsion flowoptimization, wherein the process parameters mainly include that anover-lubrication film thickness critical value of ξ_(i) ⁺ each rollingstand is and the friction coefficient at this time is u_(i) ⁺, anunder-lubrication film thickness critical value is and the frictioncoefficient at this time is u_(i) ⁻, the rolling reduction amount isΔh_(i)=h_(0i)−h_(1i), the rolling reduction rate is

${ɛ_{i} = \frac{\Delta h_{i}}{h_{0i}}},$

the inlet temperature of each rolling stand is T_(i) ^(r), the distancel=2750 mm between the rolling stands is evenly divided into m=30sections, and the temperature in the sections is represented by T_(i,j)(wherein, 1≤j≤m), and T_(i) ^(r)=T_(i−1,m), the over-lubricationjudgment coefficient is A⁺, and the under-lubrication judgmentcoefficient is A⁻;

S4, setting the initial set value of an emulsion flow rate comprehensiveoptimization objective function of a cold continuous rolling mill thataims to achieve vibration suppression as F₀=1.0×10¹⁰;

S5, calculating the bite angle α_(i) of each rolling stand according tothe rolling theory, wherein the calculation formula is

${\alpha_{i} = \sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}},$

from which it can be obtained thatα_(i)={0.0566,0.0431,0.0261,0.0227,0.0188};

S6, calculating the vibration determination index reference value ξ_(0i)of each rolling stand;

S6.1, calculating the neutral angle γ_(i) of each rolling stand, whereinthe calculation formula is

${\gamma_{i} = {\frac{1}{2}{\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}\left\lbrack {1 + {\frac{1}{2u_{i}}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}} \right\rbrack}}};$

S6.2, calculating to obtain u_(i) ⁺={0.0251,0.0187,0.0135,0.0138,0.0193}according to the formula

$u_{i}^{+} = {\frac{1}{2\left( {{2A^{+}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}$

from steps S5 and S6.1 assuming that when

${\frac{\gamma_{i}}{\alpha_{i}} = {A^{+} = 1}},$

the roll gap is just in an over-lubrication state;

S6.3, calculating an over-lubrication film thickness critical value ofξ_(i) ⁺ each rolling stand according to the relationship formula betweenthe friction coefficient and the oil film thickness, i.e.u_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) (in the formula, a_(i) is theliquid friction influence coefficient, a_(i)=0.0128, b_(i) is the dryfriction influence coefficient, b_(i)=0.1426, and B_(i) is the frictioncoefficient attenuation index, B_(i)=−2.4307), wherein the calculationformula is

${\xi_{i}^{+} = {\frac{1}{B_{i}}\ln\frac{u_{i}^{+} - a_{i}}{b_{i}}}},$

from which it can be obtained that: ξ_(i)⁺={1.011,1.321,2.253,2.041,1.272} um;

S6.4, calculating to obtain u_(i) ⁻={0.1243,0.0936,0.0664,0.0685,0.0955}according to the formula

$u_{i}^{-} = {\frac{1}{2\left( {{2A^{-}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}$

from steps S5 and S6.1 assuming that when

${\frac{\gamma_{i}}{\alpha_{i}} = {A^{-} = {0.6}}},$

the roll gap is just in an under-lubrication state;

S6.5, calculating an under-lubrication film thickness critical value ofξ_(i) ⁻ each rolling stand according to the relationship formula betweenthe friction coefficient and the oil film thickness, i.e.u_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) , wherein the calculationformula is

${\xi_{i}^{-} = {\frac{1}{B_{i}}\ln\frac{u_{i}^{-} - a_{i}}{b_{i}}}},$

from which it can be obtained that: ξ_(i)⁻={0.101,0.236,0.411,0.389,0.223} um;

S6.6, calculating the vibration determination index reference valueξ_(0i), wherein

${\xi_{0i} = \frac{\xi_{i}^{+} + \xi_{i}^{-}}{2}},$

from which it can be obtained that:ξ_(0i)={0.557,0.769,1.327,1.215,0.746};

S7, setting the emulsion flow rate of each rolling stand to bew_(i)={900,900,900,900,900} L/min;

S8, calculating the strip outlet temperature T_(i) of each rollingstand,

S8.1, calculating the outlet temperature T₁ of the first rolling stand,

$T_{1} = {{T_{1}^{r} + {\frac{1 - \left( {ɛ_{1}/4} \right)}{1 - \left( {ɛ_{1}/2} \right)} \cdot \frac{K_{1}{\ln\left( \frac{1}{1 - ɛ_{1}} \right)}}{\rho\;{SJ}}}} = {{{110} + {\frac{1 - \left( {0.43/4} \right)}{1 - \left( {0.43/2} \right)} \cdot \frac{360{\ln\left( \frac{1}{1 - {{0.4}3}} \right)}}{7.8 \cdot 0.47 \cdot 1}}} = {175.81{^\circ}\mspace{14mu}{C.}}}}$

S8.2, enabling i=1;

S8.3, calculating the temperature T_(1,1), of the first section of stripbehind the outlet of the first rolling stand, i.e. T_(i,1)=T_(i)=175.81°C.;

S8.4, enabling j=2;

S8.5, showing the relationship between the temperature of the j^(th)section and the temperature of the j−1^(th) section by the followingequation:

${T_{i,j} = {{{- \frac{2k_{0}w_{i}^{0.264}{\exp\left( {9.45 - {0.1918\mspace{14mu}{C.}}} \right)} \times 1.163l}{v_{1\; i}h_{1i}\rho Sm}}{T_{i,{j - 1}}^{- 0.213}\left( {T_{i,{j - 1}} - T_{c}} \right)}} + T_{i,{j - 1}}}},$

wherein k₀=1.0;

S8.6, determining whether the in-equation j<m is established: if yes,enabling j=j+1. and then turning to step S8.5; otherwise, turning tostep S8.7;

S8.7, obtaining the temperature T_(1,30)=105.41° C. of the m=30^(th)section by iterative calculation finally;

S8.8, calculating the inlet temperature T₂ ^(r) of the second rollingstand: T₂ ^(r)=T_(1,m)=105.41° C.;

S8.9, calculating the outlet temperature T₂ of the second rolling stand

${T_{2} = {{T_{2}^{r} + {\frac{1 - \left( {ɛ_{2}/4} \right)}{1 - \left( {ɛ_{2}/2} \right)} \cdot \frac{K_{2}{\ln\left( \frac{1}{1 - ɛ_{2}} \right)}}{\rho\;{SJ}}}} = {{{10{3.3}2} + {\frac{1 - \left( {0.45/4} \right)}{1 - \left( {0.45/2} \right)} \cdot \frac{400{\ln\left( \frac{1}{1 - {{0.4}5}} \right)}}{7800 \cdot 0.47 \cdot 1}}} = {18{2.5}2^{\circ}\mspace{14mu}{C.}}}}};$

S8.10, determining whether the in-equation i<n is established: if yes,enabling i=i+1, and then turning to step S8.3; otherwise, turning tostep S8.11;

S8.11, obtaining the outlet temperatureT_(i)=1175.86,179.36,189.77,196.65,207.541° C. of each rolling stand;

S9, calculating an emulsion flow rate comprehensive optimizationobjective function F(X);

S9.1, calculating the dynamic viscosity η_(0i) of an emulsion betweenroll gaps of each rolling stand, wherein η_(0i)=b·exp(−a·T_(i)), in theformula, a,b are the dynamic viscosity parameters of lubricating oilunder atmospheric pressure, and it can be obtained from a=0.15, b=3.0that η_(0i)={5.45,5.78,5.65,5.75,5.89};

S9.2, calculating the oil film thickness ξ_(i) between the roll gaps ofeach rolling stand according to the following formula:

$\xi_{i} = {{\frac{h_{0i} + h_{1i}}{2h_{0i}} \cdot k_{c} \cdot \frac{3\theta{\eta_{0i}\left( {v_{ri} + v_{0i}} \right)}}{\alpha_{i}\left\lbrack {1 - e^{- {\theta{({K - \frac{T_{0i}}{h_{0i} \cdot B}})}}}} \right\rbrack}} - {k_{rg} \cdot \left( {1 + K_{rs}} \right) \cdot {Ra}_{{ir}\; 0} \cdot e^{{- B_{Li}} \cdot L_{i}}}}$

wherein in the formula, k_(rg) represents the coefficient of thestrength of entrainment of lubricant by the longitudinal surfaceroughness of the work roll and the strip steel, k_(rg)=1.196, and K_(rs)represents the impression rate, that is, the ratio of transferring thesurface roughness of the working roll to the strip, K_(rs)=0.584, fromwhich it can be obtained that: ξ_(i)={0.795,0.967,2.132,2.056,1.337} um;

S9.3, calculating an emulsion flow rate comprehensive optimizationobjective function:

$\left\{ {\begin{matrix}{{F(X)} = {{\frac{\lambda}{n}{\sum\limits_{i = 1}^{n}\sqrt{\left( {\xi_{i} - \xi_{0i}} \right)^{2}}}} + {\left( {1 - \lambda} \right)\max{{\xi_{i} - \xi_{0i}}}}}} \\{\xi_{i}^{-} < \xi_{i} < \xi_{i}^{+}}\end{matrix}\quad} \right.$

in the formula, X={w_(i)} is the optimization variable, λ=0.5 is thedistribution coefficient, and thus F(X)=0.98;

S10, enabling w_(i) ^(y)=w_(i)={900,900,900,900,900} L 1 min ifF(X)=0.98<F₀=1×10¹⁰ is established, F₀=F(X)=0.98, turning to step S11,wherein in the subsequent x calculation processes, the correspondingF(X) is obtained with the change of w_(i), and the x^(th) F₀ is thex−1^(th) F(X). If the x^(th) F(X) is smaller than the x−1^(th) F(X), itis judged that F(X)<F₀ is established and turn to step S11;

S11, determining whether the emulsion flow rate w_(i) exceeds thefeasible region range. If yes, turning to step S12; otherwise, turningto step S7; and

S12, outputting an optimal emulsion flow rate set value w_(i)^(y)={1029,1055,1261,1703,1109} L/min.

Embodiment 3

In order to further explain the application process of the relatedtechnology of the present application, the application process of anemulsion flow optimization method for a cold continuous rolling millthat aims to achieve vibration suppression is described by taking a 1220cold continuous rolling mill in a cold rolling plant as an example.

An emulsion flow optimization method for suppressing vibration of a coldcontinuous rolling mill includes the following steps:

S1, collecting device feature parameters of the cold continuous rollingmill, wherein the 1220 cold continuous rolling mill in a cold rollingplant has 5 rolling stands in total, and the device feature parametersmainly include: the radius R_(i)={208,210,227,226,225} mm of a workingroll of each rolling stand, the surface linear velocityν_(ri)={176,317,495,789,1146} m/min of a roll of each rolling stand, theoriginal roughness Ra_(ir0)={0.9,0.9,0.7,0.7,0.8} um of a working rollof each rolling stand, the roughness attenuation coefficient B_(L)=0.01of a working roll, the distance l=2700 mm between rolling stands, andthe rolling kilometer L_(i)={152,102,215,165,70} km after roll change ofa working roll of each rolling stand, wherein i is 1, 2, . . . , n, andrepresents the ordinal number of rolling stands of the cold continuousrolling mill, and n=5 is the total number of rolling stands, the samebelow;

S2, collecting key rolling process parameters of a strip, wherein thekey rolling process parameters mainly include: the inlet thicknessh_(0i)={1.8,1.05,0.57,0.39,0.25} mm of each rolling stand, the outletthickness h_(1i)={1.05,0.57,0.36,0.22,0.13} mm of each rolling stand,strip width B=876 mm, the inlet speed ν_(0i)={104,185,337,546,844} m/minof each rolling stand, the outlet speedν_(1i)={188,337,548,845,1201}m/min of each rolling stand, the inlettemperature T₁ ^(r)=110° C., strip deformation resistanceK_(i)={355,395,476,580,640} MPa of each rolling stand, rolling pressureP_(i)={12900,11200,10400,9600,8900} kN of each rolling stand, backtension T_(0i)={74,141,203,201,219} MPa of each rolling stand, fronttension T_(1i){140,203,199,224,50} MPa of each rolling stand, emulsionconcentration influence coefficient k_(c)=0.8, pressure-viscositycoefficient θ=0.035 of a lubricant, strip density ρ=7800 kg/m³, specificheat capacity S=0.45 kJ/(kg·° C.) of a strip, emulsion concentrationC=3.7%, emulsion temperature T_(c)=55° C. and thermal-work equivalentJ=1;

S3, defining process parameters involved in the process of emulsion flowoptimization, wherein the process parameters mainly include that anover-lubrication film thickness critical value of ξ_(i) ⁺ each rollingstand is and the friction coefficient at this time is u_(i) ⁺, anunder-lubrication film thickness critical value ξ_(i) ⁻ is and thefriction coefficient at this time is u_(i) ⁻, the rolling reductionamount is Δh_(i)=h_(0i)−h_(1i), the rolling reduction rate is

${ɛ_{i} = \frac{\Delta\; h_{i}}{h_{0i}}},$

the inlet temperature of each rolling stand is T_(i) ^(r), the distancel=2700 mm between the rolling stands is evenly divided into m=30sections, and the temperature in the sections is represented by T_(i,j)(wherein, 1≤j≤m), and T_(i) ^(r)=T_(i−1,m), the over-lubricationjudgment coefficient is A⁺, and the under-lubrication judgmentcoefficient is A⁻;

S4, setting the initial set value of an emulsion flow rate comprehensiveoptimization objective function of a cold continuous rolling mill thataims to achieve vibration suppression as F₀=1.0×10¹⁰;

S5, calculating the bite angle α_(i) of each rolling stand according tothe rolling theory, wherein the calculation formula is

${\alpha_{i} = \sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}},$

from which it can be obtained thatα_(i)={0.0546,0.0406,0.0247,0.0220,0.0179};

S6, calculating the vibration determination index reference value ξ_(0i)of each rolling stand;

S6.1, calculating the neutral angle γ_(i) of each rolling stand, whereinthe calculation formula is

${\gamma_{i} = {\frac{1}{2}{\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}\left\lbrack {1 + {\frac{1}{2u_{i}}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}} \right\rbrack}}};$

S6.2, calculating to obtain u_(i) ⁺={0.0242,0.0179,0.0127,0.0130,0.0185}according to the formula

$u_{i}^{+} = {\frac{1}{2\left( {{2A^{+}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}$

from steps S5 and S6.1 assuming that when

${\frac{\gamma_{i}}{\alpha_{i}} = {A^{+} = 1}},$

the roll gap is just in an over-lubrication state;

S6.3, calculating an over-lubrication film thickness critical value ofξ_(i) ⁺ each rolling stand according to the relationship formula betweenthe friction coefficient and the oil film thickness, i.e.u_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) (in the formula, a_(i) is theliquid friction influence coefficient, a_(i)=0.0125, b_(i) is the dryfriction influence coefficient, b_(i)=0.1414, and B_(i) is the frictioncoefficient attenuation index, B_(i)=−2.4280), wherein the calculationformula is

${\xi_{i}^{+} = {\frac{1}{B_{i}}\ln\frac{u_{i}^{+} - a_{i}}{b_{i}}}},$

from which it can be obtained that: ξ_(i)⁻={1.001,1.289,2.232,2.037,1.268} um;

S6.4, calculating to obtain u_(i) ⁻={0.1241,0.0922,0.0610,0.0630,0.0935}according to the formula

$u_{i}^{-}\frac{1}{2\left( {{2A^{-}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)$

from steps S5 and S6.1 assuming that when

${\frac{\gamma_{i}}{\alpha_{i}} = {A^{-} = {0.6}}},$

the roll gap is just in an under-lubrication state;

S6.5, calculating an under-lubrication film thickness critical value ofξ_(i) ⁻ each rolling stand according to the relationship between thefriction coefficient and the oil film thickness, i.e.u_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) , wherein the calculationformula is

${\xi_{i}^{-} = {\frac{1}{B_{i}}\ln\frac{u_{i}^{-} - a_{i}}{b_{i}}}},$

from which it can be obtained that: ξ_(i)⁻:={0.097,0.223,0.398,0.385,0.210} um;

S6.6, calculating the vibration determination index reference valueξ_(0i), wherein

${\xi_{0i} = \frac{\xi_{i}^{+} + \xi_{i}^{-}}{2}},$

from which it can be obtained that:ξ_(0i)={0.548,0.762,1.321,1.207,0.736};

S7, setting the emulsion flow rate of each rolling stand to bew_(i)={900,900,900,900,900} L/min;

S8, calculating the strip outlet temperature T_(i) of each rollingstand,

S8.1, calculating the outlet temperature T₁ of the first rolling stand,

$T_{1} = {{T_{1}^{r} + {\frac{1 - \left( {ɛ_{1}/4} \right)}{1 - \left( {ɛ_{1}/2} \right)} \cdot \frac{K_{1}{\ln\left( \frac{1}{1 - ɛ_{1}} \right)}}{\rho\;{SJ}}}} = {{{110} + {\frac{1 - \left( {0.43/4} \right)}{1 - \left( {0.43/2} \right)} \cdot \frac{360{\ln\left( \frac{1}{1 - {{0.4}3}} \right)}}{7.8 \cdot 0.47 \cdot 1}}} = {169.96{^\circ}\mspace{14mu}{C.}}}}$

S8.2, enabling i=1;

S8.3, calculating the temperature T_(1,1), of the first section of stripbehind the outlet of the first rolling stand, i.e. T_(i,1)=T_(i)=169.96°C.;

S8.4, enabling j=2;

S8.5, showing the relationship between the temperature of the j^(th)section and the temperature of the j−1^(th) section by the followingequation:

${T_{i,j} = {{{- \frac{2k_{0}w_{i}^{0.264}{\exp\left( {9.45 - {0.1918\mspace{14mu}{C.}}} \right)} \times 1.163l}{v_{1i}h_{1i}\rho Sm}}{T_{i,{j - 1}}^{- 0.213}\left( {T_{i,{j - 1}} - T_{c}} \right)}} + T_{i,{j - 1}}}},$

wherein k₀=1.0;

S8.6, determining whether the in-equation j<m is established: if yes,enabling j=j+1. and then turning to step S8.5; otherwise, turning tostep S8.7;

S8.7, obtaining the temperature T_(1,30)=101.25° C. of the m=30^(th)section by iterative calculation finally;

S8.8, calculating the inlet temperature T₂ ^(r) of the second rollingstand: T₂ ^(r)=T_(1,m)=101.25° C.;

S8.9, calculating the outlet temperature T₂ of the second rolling stand:

${T_{2} = {{T_{2}^{r} + {\frac{1 - \left( {ɛ_{2}/4} \right)}{1 - \left( {ɛ_{2}/2} \right)} \cdot \frac{K_{2}{\ln\left( \frac{1}{1 - ɛ_{2}} \right)}}{\rho\;{SJ}}}} = {{{10{3.3}2} + {\frac{1 - \left( {0.45/4} \right)}{1 - \left( {0.45/2} \right)} \cdot \frac{400{\ln\left( \frac{1}{1 - {{0.4}5}} \right)}}{7800 \cdot 0.47 \cdot 1}}} = {175.86{^\circ}\mspace{14mu}{C.}}}}};$

S8.10, determining whether the in-equation i<n is established: if yes,enabling i=i+1, and then turning to step S8.3; otherwise, turning tostep S8.11;

S8.11, obtaining the outlet temperatureT_(i)={177.96,172.78,184.59,191.77,203.33}° C. of each rolling stand;

S9, calculating an emulsion flow rate comprehensive optimizationobjective function F(X);

S9.1, calculating the dynamic viscosity η_(0i) of an emulsion betweenroll gaps of each rolling stand, wherein η_(0i)=b·exp(−a·T_(i)), in theformula, a,b are the dynamic viscosity parameter of lubricating oilunder atmospheric pressure, and it can be obtained from a=0.15, b=2.0that η_(0i)={5.45,5.02,5.98,5.45,5.76};

S9.2, calculating the oil film thickness ξ_(i) between the roll gaps ofeach rolling stand according to the following formula:

$\xi_{i} = {{\frac{h_{0i} + h_{1i}}{2h_{0i}} \cdot k_{c} \cdot \frac{3\theta{\eta_{0i}\left( {v_{ri} + v_{0i}} \right)}}{\alpha_{i}\left\lbrack {1 - e^{- {\theta{({K - \frac{T_{0i}}{h_{0i} \cdot B}})}}}} \right\rbrack}} - {k_{rg} \cdot \left( {1 + K_{rs}} \right) \cdot {Ra}_{{ir}\; 0} \cdot e^{{- B_{Li}} \cdot L_{i}}}}$

wherein in the formula, k_(rg) represents the coefficient of thestrength of entrainment of lubricant by the longitudinal surfaceroughness of the work roll and the strip steel, k_(rg)=1.165, and K_(rs)represents the impression rate, that is, the ratio of transferring thesurface roughness of the working roll to the strip, k_(rs)=0.566, fromwhich it can be obtained that: ξ_(i)={0.774,0.926,2.088,2.032,1.318} um;

S9.3, calculating an emulsion flow rate comprehensive optimizationobjective function:

$\left\{ {\begin{matrix}{{F(X)} = {{\frac{\lambda}{n}{\sum\limits_{i = 1}^{n}\sqrt{\left( {\xi_{i} - \xi_{0i}} \right)^{2}}}} + {\left( {1 - \lambda} \right)\max{{\xi_{i} - \xi_{0i}}}}}} \\{\xi_{i}^{-} < \xi_{i} < \xi_{i}^{+}}\end{matrix}\quad} \right.$

In the formula, X={w_(i)} is the optimization variable, λ=0.5 is thedistribution coefficient, and thus F(X)=0.91;

S10, enabling w_(i) ^(y)=w_(i)={900,900,900,900,900} L/min ifF(X)=0.91<F₀=1×10¹⁰ is established, F₀=F(X)=0.91, turning to step S11,wherein in the subsequent x calculation processes, the correspondingF(X) is obtained with the change of w_(i), and the x^(th) F₀ is thex−1^(th) F(X). If the x^(th) F(X) is smaller than the x−1^(th) F(X), itis judged that F(X)<F₀ is established and turn to step S11;

S11, determining whether the emulsion flow rate w_(i) exceeds thefeasible region range. If yes, turning to step S12; otherwise, turningto step S7; and

S12, outputting an optimal emulsion flow rate set value w_(i)^(y)={1016,1040,1266,1681,1111} L/min.

The invention is applied to the five-machine-frame cold continuousrolling mills 1730, 1420 and 1220 in the cold rolling plant. Accordingto the production experience of the cold rolling plant, the solution ofthe invention is feasible, and the effect is very obvious. The inventioncan be further applied to other cold continuous rolling mills, and thepopularization prospect is relatively broad.

To sum up, the technical solution of the invention is adopted, and theemulsion flow optimization method for suppressing vibration of the coldcontinuous rolling mill fully combines the device and process featuresof the cold continuous rolling mill, and aiming at the vibration defectproblem, starting from the comprehensive optimization setting of theemulsion flow rate of each rolling stand, the method changes theprevious idea of constant emulsion flow control for each rolling standof the cold continuous rolling mill, and obtains the optimal set valueof the emulsion flow rate for each rolling stand that aims to achievevibration suppression by optimization; and the method greatly reducesthe incidence of rolling mill vibration defects, improves productionefficiency and product quality, and brings greater economic benefits forenterprises; and achieves the treatment for rolling mill vibrationdefects, and improves the surface quality and rolling process stabilityof a finished strip of a cold continuous rolling mill.

1. An emulsion flow optimization method for suppressing vibration of acold continuous rolling mill, characterized by comprising the followingsteps: (S1) collecting device feature parameters of the cold continuousrolling mill, wherein the device feature parameters comprise: the radiusR_(i) of a working roll of each rolling stand, the surface linearvelocity ν_(ri) of a roll of each rolling stand, the original roughnessRa_(ir0) of a working roll of each rolling stand, roughness attenuationcoefficient B_(L) of a working roll, the distance l between rollingstands, and the rolling kilometer L_(i) after roll change of a workingroll of each rolling stand, wherein i is 1, 2, . . . , n, and representsthe ordinal number of the rolling stands of the cold continuous rollingmill, and n is the total number of rolling stands; (S2) collecting keyrolling process parameters of a strip, wherein the key rolling processparameters comprise: the inlet thickness h_(0i) of each rolling stand,the outlet thickness h_(1i) of each rolling stand, strip width B, theinlet speed ν_(0i) of each rolling stand, the outlet speed ν_(1i) ofeach rolling stand, the inlet temperature T₁ ^(r), strip deformationresistance K_(i) of each rolling stand, rolling pressure P_(i) of eachrolling stand, back tension T_(0i) of each rolling stand, front tensionT_(1i) of each rolling stand, emulsion concentration influencecoefficient k_(c), pressure-viscosity coefficient θ of a lubricant,strip density ρ, specific heat capacity S of a strip, emulsionconcentration C, emulsion temperature T_(c) and thermal-work equivalentJ; (S3) defining process parameters involved in the emulsion flowoptimization process, wherein the process parameters comprise anover-lubrication film thickness critical value ξ_(i) ⁺ of each rollingstand, the friction coefficient u_(i) ⁺ at this time, anunder-lubrication film thickness critical value ξ_(i) ⁻ and the frictioncoefficient u_(i) ⁻ at this time, the rolling reduction amount Δh_(i)(wherein Δh_(i)=h_(0i)−h_(1i)), the rolling reduction rate ε_(i)(wherein $\left. {ɛ_{i} = \frac{\Delta h_{i}}{h_{0i}}} \right),$ theinlet temperature T_(i) ^(r) of each rolling stand, the over-lubricationjudgment coefficient A⁺, and the under-lubrication judgment coefficientA⁻, and evenly dividing the distance l between the rolling stands into msections, wherein the temperature in the sections is represented byT_(i,j) (wherein 1≤j≤m), and T_(i) ^(r)=T_(i−1,m)); (S4) setting theinitial set value of an emulsion flow rate comprehensive optimizationobjective function of the cold continuous rolling mill for achievingvibration suppression as F₀=1.0×10¹⁰; wherein the executing order ofsteps S1-S4 is not limited; (S5) calculating the bite angle α_(i) ofeach rolling stand according to the rolling theory, wherein thecalculation formula is as follows:${\alpha_{i} = \sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}},$ R_(i)′ isthe flattening radius of the working roll of the i^(th) rolling stand,and is a calculation process value of rolling pressure; (S6) calculatingthe vibration determination index reference value ξ_(0i) of each rollingstand; (S7) setting the emulsion flow rate w_(i) of each rolling stand;(S8) calculating the strip outlet temperature T_(i) of each rollingstand; (S9) calculating an emulsion flow rate comprehensive optimizationobjective function F(X); $\left\{ {\begin{matrix}{{F(X)} = {{\frac{\lambda}{n}{\sum\limits_{i = 1}^{n}\sqrt{\left( {\xi_{i} - \xi_{0i}} \right)^{2}}}} + {\left( {1 - \lambda} \right)\max{{\xi_{i} - \xi_{0i}}}}}} \\{\xi_{i}^{-} < \xi_{i} < \xi_{i}^{+}}\end{matrix};} \right.$ (S10) determining whether the in-equationF(X)<F₀ is established, if yes, enabling w_(i) ^(y)=w_(i), F₀=F(X), andturning to step S11; otherwise, directly turning to step S11; (S11)determining whether the emulsion flow rate w_(i) exceeds a feasibleregion range, if yes, turning to step S12, otherwise, turning to stepS7, wherein the feasible region of w_(i) ranges from 0 to the maximumemulsion flow rate value allowed by the rolling mill; and (S12)outputting an optimum emulsion flow rate set value w_(i) ^(y), whereinw_(i) ^(y) is the value of w_(i) when the calculated value of F(X) inthe feasible region is minimum.
 2. The emulsion flow optimization methodfor suppressing vibration of a cold continuous rolling mill according toclaim 1, characterized in that, the step S6 comprises the followingsteps: (S6.1) calculating the neutral angle γ_(i) of each rolling stand:${\gamma_{i} = {\frac{1}{2}{\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}}\left\lbrack {1 + {\frac{1}{2u_{i}}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}} \right\rbrack}}};$(S6.2) calculating to obtain$u_{i}^{+} = {\frac{1}{2\left( {{2A^{+}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}$from the step S5 and the step S6.1 assuming that when${\frac{\gamma_{i}}{\alpha_{i}} = A^{+}},$ the roll gap is just in anover-lubrication state; (S6.3) calculating an over-lubrication filmthickness critical value ξ_(i) ⁺ of each rolling stand according to therelation formula between the friction coefficient and the oil filmthickness, i.e. u_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) (in the formula,a_(i) is a liquid friction influence coefficient, b_(i) is a dryfriction influence coefficient, and B_(i) is a friction coefficientattenuation index), wherein${\xi_{i}^{+} = {\frac{1}{B_{i}}\ln\frac{u_{i}^{+} - a_{i}}{b_{i}}}};$(S6.4) calculating to obtain$u_{i}^{-} = {\frac{1}{2\left( {{2A^{-}} - 1} \right)}\left( {\sqrt{\frac{\Delta\; h_{i}}{R_{i}^{\prime}}} + \frac{T_{i\; 0} - T_{i\; 1}}{P_{i}}} \right)}$from the step S5 and the step S6.1 assuming that when${\frac{\gamma_{i}}{\alpha_{i}} = A^{-}},$ the roll gap is just in anunder-lubrication state; (S6.5) calculating an under-lubrication filmthickness critical value ξ_(i) ⁻ of each rolling stand according to therelation formula between the friction coefficient and the oil filmthickness, i.e. u_(i)=a_(i)+b_(i)·e^(B) ^(i) ^(·ξ) ^(i) , wherein${\xi_{i}^{-} = {\frac{1}{B_{i}}\ln\frac{u_{i}^{-} - a_{i}}{b_{i}}}};$and (S6.6) calculating the vibration determination index reference valueξ_(0i), wherein $\xi_{0\; i} = {\frac{\xi_{i}^{+} + \xi_{i}^{-}}{2}.}$3. The emulsion flow optimization method for suppressing vibration of acold continuous rolling mill according to claim 2, characterized inthat, the step S8 comprises the following steps: (S8.1) calculating theoutlet temperature T₁ of the first rolling stand, wherein${T_{1} = {T_{1}^{r} + {\frac{1 - \left( {ɛ_{1}/4} \right)}{1 - \left( {ɛ_{1}/2} \right)} \cdot \frac{K_{1}{\ln\left( \frac{1}{1 - ɛ_{1}} \right)}}{\rho\;{SJ}}}}};$(S8.2) enabling i=1; (S8.3) calculating the temperature T_(i,1) of thefirst section of strip behind the outlet of the i^(th) rolling stand,i.e. T_(i,1)=T_(i); (S8.4) enabling j=2; (S8.5) calculating thetemperature T_(i,j) of the j^(th) section of strip by the relationshipbetween the temperature of the j^(th) section and the temperature of thej−1^(th) section shown by the following equation:${T_{i,j} = {{{- \frac{2k_{0}w_{i}^{0.264}{\exp\left( {9.45 - {{0.1}918\mspace{14mu}{C.}}} \right)} \times {1.1}63l}{v_{1i}h_{1i}\rho Sm}}{T_{i,{j - 1}}^{- 0.213}\left( {T_{i,{j - 1}} - T_{c}} \right)}} + T_{i,{j - 1}}}},$wherein k₀ is the influence coefficient of nozzle shape and sprayingangle; (S8.6) determining whether the in-equation j<m is established, ifyes, enabling j=j+1, and then turning to step S8.5; otherwise, turningto step S8.7; (S8.7) obtaining the temperature T_(i,m) of the m^(th)section by iterative calculation; (S8.8) calculating the inlettemperature T_(i+1) ^(r) of the i+1^(th) rolling stand: T_(i+1)^(r)=T_(i,m); (S8.9), calculating the outlet temperature T_(i+1) of thei+1^(th) rolling stand, wherein${T_{i + 1} = {T_{i + 1}^{r} + {\frac{1 - \left( {ɛ_{i + 1}/4} \right)}{1 - \left( {ɛ_{i + 1}/2} \right)} \cdot \frac{K_{i + 1}{\ln\left( \frac{1}{1 - ɛ_{i + 1}} \right)}}{\rho\;{SJ}}}}};$(S8.10) determining whether the in-equation i<n is established, if yes,enabling i=i+1, and then turning to step S8.3; otherwise, turning tostep S8.11; and (S8.11) obtaining the outlet temperature T_(i) of eachrolling stand.
 4. The emulsion flow optimization method for suppressingvibration of a cold continuous rolling mill according to claim 3,characterized in that, the step S9 comprises the following steps: (S9.1)calculating the dynamic viscosity η_(0i) of an emulsion between rollgaps of each rolling stand, wherein η_(0i)=b·exp(−a·T_(i)), and in theformula, a,b are dynamic viscosity parameters of lubricating oil underthe atmospheric pressure; (S9.2) calculating the oil film thicknessξ_(i) between roll gaps of each rolling stand, wherein the calculationformula is as follows:$\xi_{i} = {{\frac{h_{0\; i} + h_{1i}}{2h_{0\; i}} \cdot k_{c} \cdot \frac{3\theta{\eta_{0i}\left( {v_{ri} + v_{0i}} \right)}}{\alpha_{i}\left\lbrack {1 - e^{- {\theta{({K - \frac{T_{0i}}{h_{0i} \cdot B}})}}}} \right\rbrack}} - {k_{rg} \cdot \left( {1 + K_{rs}} \right) \cdot {Ra}_{{ir}\; 0} \cdot e^{{- B_{L}} \cdot L_{i}}}}$in the formula, k_(rg) represents the coefficient of the strength ofentrainment of lubricant by the longitudinal surface roughness of thework roll and the strip steel and is in the range of 0.09-0.15, K_(rs)represents the impression rate, namely the ratio of transferring thesurface roughness of the working roll to the strip; and (S9.3)calculating an emulsion flow rate comprehensive optimization objectivefunction, $\left\{ {\begin{matrix}{{F(X)} = {{\frac{\lambda}{n}{\sum\limits_{i = 1}^{n}\sqrt{\left( {\xi_{i} - \xi_{0i}} \right)^{2}}}} + {\left( {1 - \lambda} \right)\max{{\xi_{i} - \xi_{0i}}}}}} \\{\xi_{i}^{-} < \xi_{i} < \xi_{i}^{+}}\end{matrix}\quad} \right.$ in the formula, X={w_(i)} is an optimizationvariable, and λ is a distribution coefficient.
 5. The emulsion flowoptimization method for suppressing vibration of a cold continuousrolling mill according to claim 3, characterized in that, 0.8<k₀<1.2.